The Planet Earth

bismillah ar-rahman ar-rahim .

jai as-salamu alaikum .

today the topic that i will be talking about is the planet earth .

in the vast gigantic and expanding universe , the only planet that we have which is full of life is the planet earth , the only home in the universe .

today i will be talking about this planet , our only home in the universe .

so before going into details , i will let you talk about a few things .

we already are familiar with the word sphere .

sphere is any three dimensional body .

we can say that it is any three dimensional body .

so when we talk about the globe , we have divided the globe into different spheres .

okay .

and the most common everyone of you knows that we have north pole on one side and the south pole on the other side of the globe .

this is the normal division that we have of the globe .

and then we divide the whole earth into two spheres , hemispheres .

in fact , hemi means half and sphere means again i will talk about the portion .

so we have the northern hemisphere and we have the southern hemisphere .

so these are the two major divisions of the planet earth when we discuss or when we study planet earth globally .

and if you see more importantly very closely then you can see on the northern hemisphere , the northern part we have most of the land masses .

the land mass , most of the land mass is on the northern side .

you can see from this and this or the northern side has most of the land masses while the southern side has most of the ocean .

so this is one of the major difference between the north and the south hemispheres .

and again the climate is also very different .

when there is winter in the northern hemisphere , it's summer in the southern hemisphere .

this is one divinium when we talk about earth .

another divinium which is related to this is the eastern hemisphere and the western hemisphere .

so , eastern hemisphere contains all the countries towards the east , towards the east eastern side and the western hemisphere contain all the countries on the west side which means in the western hemisphere we have north and south america and in the eastern side we have asia and other countries .

so this is another division of earth .

then there is another division which is known as the land hemisphere and the water hemisphere .

so you can see all the water on one side like this , all the water bodies on one side and then all the land on one side .

so this is the land hemisphere when we talk about the land .

so these are further some divisions of earth .

i have told you about northern hemisphere , southern hemisphere , then we have northern hemisphere , southern hemisphere , then i talked about eastern hemisphere and the western hemisphere , then i talked about the land hemisphere and the ocean hemisphere .

so these are the few divisions that how we study the earth .

now coming back to the planet earth , there are four major spheres within the planet earth that we study and that are of very prime importance and those are atmosphere , lithosphere , biosphere and hydrosphere .

these are the four main spheres when we are studying earth .

and before going into details of these four spheres , there is one important term that i would like to mention here and that is the natural resources .

resources or natural resources are any material substance that are useful or beneficial for human beings .

so when we talk about natural these means that they are present naturally in the environment .

and atmosphere is mixture of gases we all know and from you can see from the ground up to 60,000 kilometers , it is our atmosphere .

and the atmosphere further consists of different layers .

it consists of troposphere , stratosphere , mesosphere , thermosphere , ionosphere , and so on and so forth .

and then this atmosphere consists of gases .

all the gases that we see , nitrogen is almost 98% , 21% is oxygen .

so these gases , these are the resources of atmosphere .

and this is one of the very important spheres of the planet earth because all the climate , all the weather is related with the atmosphere .

the second most important sphere of the earth is the hydrosphere and you know 70% of the world is water and so water bodies , the oceans , they come under the hydrosphere .

and then very important , the natural resources of the sphere of water , when i would talk about that , the salts , the different chemicals that are present in the ocean water , they are the natural resources of the hydrosphere .

different kinds of salts that are present in the ocean bodies , different salts or different stones that are present within the water body .

so when we talk about lithosphere , lithosphere , litho means soil and sphere of soil .

so all the land masses comes under the lithosphere , all the rocks and the most important natural resources are the fossil fuels that we get from the lithosphere , the oil , coal and gas .

these are one of the major important natural resources from the lithosphere .

and then we have all the minerals , we have all , you can say , different metals that are coming from the lithosphere .

they are all resources of lithosphere .

and finally , we talk about biosphere .

biosphere is the sphere of life which consists of all the animals , all the plants .

so they are a very important resource and all the life that we see on the planet earth comes under the biosphere .

these are the four major spheres when we talk about .

and furthermore if you see the divines , we already know that there are six main continents in the world and seven major oceans .

in urdu normally we say that saath samandar par kui rehta hai or saath samandar .

so we mentioned this term .

so the main six continents that we see in the world are north america , south america , asia , europe , australia , africa .

africa .

but in certain books there is a further , there is a little bit difference , a division of the continents and some books combine asia and europe together and they make it eurasia and they have antarctica as the sixth continent .

however , you will see this kind of this division in different books , the both that i have described you .

and when we talk about the seven seas , then we have the indian ocean , we have the pacific ocean , we have north atlantic ocean and south atlantic ocean , then we have a mediterranean sea which is also present between africa and europe but it's also clear as a separate ocean .

we have a southern ocean and we have arctic ocean .

so all seven makes the seven seas .

in this , the mediterranean sea is the one which is present between africa and europe and it's also considered as the seventh ocean in the world .

although it's not an ocean , not as big as an ocean but it is considered as one of the water , seventh water body in the world .

so these are the major divisions when we talk about planet earth .

i have described you about the different hemispheres , then different spheres within the earth .

so these are the primary , you can say , primary division when we study the planet earth and i hope in future we will be talking more about these spheres and interaction of atmosphere , biosphere , lithosphere and hydrosphere in more detail .

there is another crude term which is also used in some books and that is cryosphere , the sphere of ice but again it is related with the hydrosphere so you can you might see some differentiation in certain books because all the water sheets the north pole and south pole which are continuously covered with ice they are considered sometimes as separate sphere known as cryosphere .

but these are the four major spheres that we already study in different books .

so i hope this is a good , i hope you will have a good understanding of the different sphere that i have talked about and in future lectures we will be talking about these phase in detail .

thank you very much .